Hard/soft superposition progressive lens design

Abstract

A progressive ophthalmic lens is presented which is a linear composite of a hard lens design and a soft lens design resulting in a composite lens which combines features of the visual utility of a hard lens design with the visual comfort of a soft lens design.

What is claimed is: 
     
       1. A progressive ophthalmic lens having: a distance portion, a reading portion and an intermediate portion;   the lens having a composite progressive power surface Z C  defined by the equation:   Z.sub.C.sup.(A) =Z.sub.H.sup.(A--B) +Z.sub.X.sup.(B) -Z.sub.H.sup.(0)     where:     Z C  =elevation of the progressive power surface above a reference plane;   Z H  =elevation of the progressive power surface above said reference plane for a first design component of the lens;   Z S  =elevation of the progressive power surface above said reference plane for a second design component of the lens;   A=the power addition of the composite lens; and   B=the power addition of said second design component.   
     
     
       2. The progressive ophthalmic lens of claim 1 wherein: the power addition B is not more than 1.25 diopters.   
     
     
       3. The progressive ophthalmic lens of claim 1 wherein: said first design component is a hard design component, and said second design component is a soft design component.   
     
     
       4. The method of defining a composite progressive power surface of a progressive ophthalmic lens having a distance portion, a reading portion, and an intermediate portion, including the steps of: defining a first design component of addition A--B,   defining a second design component of addition B, and   defining a composite progressive power surface Z C  according to the equation:   Z.sub.C.sup.(A) =Z.sub.H.sup.(A--B) +Z.sub.S.sup.(B) -Z.sub.H.sup.(0)     where:     Z C  =elevation of the progressive power surface above a reference plane;   Z H  =elevation of the progressive power surface above said reference plane for a first design component of the lens;   Z S  =elevation of the progressive power surface above said reference plane for a second design component of the lens;   A=the power addition of the composite lens; and   B=the power addition of said second design component.   
     
     
       5. The method of claim 4 wherein: the power addition B is not more than 1.25 diopters.   
     
     
       6. The method of claim 4 wherein: said first design component is a hard design component, and said second design component is a soft design component.